I've just faced a wierd problem with my tranny.
Actually, yesterday it was raining and I thought that rear end is slipping on the road, but I found out that all of a sudden my tranny is slipping and it is heating up. It went upto 200 almost!!!

So I checked the fluid, it's full.
It looks fine, and it doesn't smell like a burned out tranny fluid.

This morning when I ran the car it's a '70 1/2 Camaro SS 350, it was o.k. again.
As I drove it for about an hour of so again, I faced the same problem. It gets heated and it starts slipping.

When I'm in a steep road and when in Drive, as soon as I take my foot of the break, the car eventhough in Drive it starts to go backward down the road. So for the car to start moving forward I'd have to almost rev. about 3000 rpm to move forward.

Today, I opened up the oil pan, the oil was just in perfect condition, and there were no worn out clutch particles in the filter and/or oil pan at all!!!
As I mentioned earlier this tranny has been rebuilt for about three months ago or app. 1000 miles.

So I opened the valve body, checked all the valves and springs. Everything was just fine.
The vacuum modulator had sucked in some trans fluid, I don't know why!!!
Tomorrow I'm gonna change the modulator, but does it have anything to do with this problem?

So, now, what do you guys suggest?
Should I take out the tranny and open up the front pump, bands, etc.?

Or could it be the Torque Converter?

Any guesses, advises.
BTW, I changed the fluid as well and pumped up air through all the cooler lines too. So there should be no problem there either.

Today, I opened up the oil pan, the oil was just in perfect condition, and there were no worn out clutch particles in the filter and/or oil pan at all!!!
As I mentioned earlier this tranny has been rebuilt for about three months ago or app. 1000 miles.

So I opened the valve body, checked all the valves and springs. Everything was just fine.
The vacuum modulator had sucked in some trans fluid, I don't know why!!!
Tomorrow I'm gonna change the modulator, but does it have anything to do with this problem?

So, now, what do you guys suggest?
Should I take out the tranny and open up the front pump, bands, etc.?

Or could it be the Torque Converter?

Any guesses, advises.
BTW, I changed the fluid as well and pumped up air through all the cooler lines too. So there should be no problem there either.

Thanks in advance for your assistance.

Houman SS '70

RE: our PM's on this subject..... did you test reverse gear? Does it work when the forwards gears fail?

Have you run pressure tests when the trans fails to move correctly?

__________________Dont worry how old you are... it is the mileage on your body that adds up.

Hi,
I had a similar problem with the turbo 400 in my '72.
The trans had around 2500 miles use (albeit HARD use, behind a 455 Olds) after a rebuild when it was parked for 6 years. When it was started and driven after sitting, it would barely move in D and only after it revved to around 3000 rpm, then it would drive alright till it sat idling in park for a little while. I suspected either slipping or or lack of fluid pressure.

When the trans was torn down for a rebuild, it ended up having the clutches and internals which looked great, but the seals had went bad after sitting and caused lack of proper fluid pressure. I thought the trans was slipping and torched but it turned out not to be the case.

Hi,
I had a similar problem with the turbo 400 in my '72.
The trans had around 2500 miles use (albeit HARD use, behind a 455 Olds) after a rebuild when it was parked for 6 years. When it was started and driven after sitting, it would barely move in D and only after it revved to around 3000 rpm, then it would drive alright till it sat idling in park for a little while. I suspected either slipping or or lack of fluid pressure.

When the trans was torn down for a rebuild, it ended up having the clutches and internals which looked great, but the seals had went bad after sitting and caused lack of proper fluid pressure. I thought the trans was slipping and torched but it turned out not to be the case.

Anyways, a rebuild would solve it.

Cheers,
Andy

Hey Andy,

Thanks for your reply.

Today, I tore down the tranny.

The converter was o.k. and had no problem at all, and as I mentioned earlier, I had opened up the valve body and they were o.k. too.

So what was left? The clutches and the pump.

Guess what?
The first ring on the pump ( actually you can call it the first or the last depends where you start) the one at the tip of the pump shaft was broken!!!

I really don't know why, but anyway the pump shaft was also damaged, so I had to use another pump which I got out of a healthy tranny.

A couple of the clutches had changed color as well, but not really that much, so I replaced them as well and now the tranny is running fine again.
My tranny expert used teflon rings this time, he said at least the teflon rings if broken, they won't damage other things.
Do you have any comments about the teflon rings? Are they better???

I got a small problem and that is, the tranny does not shift as hard (firm) as it did before this damage.
What is it? I didn't get the time to tune the vacuum modulator screw, could it be that?

You know, my car would smoke when wot in 1st, but now it will not smoke, it will take off, but no smoke.

Houman,
I don't really have any idea why you car would or would not smoke while at WOT, unless you just replaced the vacuum modulator. In this case you were most likely sucking tranny fluid out the ruptured diaphragm and this was causing the smoke.

About the teflon rings, I have heard they work well, but I have only built manual transmissions so I don't have any direct experience. I do have teflon rings in my TH-400, however, and no problems.

For shift quality, they are lot of variables which can affect this. If the trans was shifting hard prior to modulator replacement, it will shift less firmly than before once replaced. You could adjust it back to previous firmness as long as the range of adjustment is within the engine vacuum you have. If there is less vacuum vs. more, the shift quality will be harder.

It sounds like everything is under control. Makes me want to try my hand at building another th-400 as a spare for my ride. Any leads on a turbo-400 with a BOP bolt pattern.

If the car was sitting for awhile, and smoking under WOT, thrash it a little bit with a couple 0-80 WOT runs. After running it out like this it often cleans out crap from the engine. Plus, it is really fun.....

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